1. Field of the Invention
The present invention relates to a refrigeration cycle device with an ejector having a refrigerant decompression function and a refrigerant circulating function.
2. Description of the Related Art
A vapor-compression type refrigeration cycle device using an ejector is disclosed in JP-B1-3322263 (corresponding to U.S. Pat. No. 6,477,857 and U.S. Pat. No. 6,574,987). In JP-B1-3322263, the refrigeration cycle device includes a first evaporator disposed on a downstream side of a refrigerant flow of an ejector serving as a refrigerant decompression means and a refrigerant circulating means, and a vapor-liquid separator is located at a refrigerant outlet side of the first evaporator. Furthermore, a second evaporator is disposed between a liquid refrigerant outlet of the vapor-liquid separator and a refrigerant suction port of the ejector.
In the refrigeration cycle device disclosed in JP-B1-3322263, by using a decrease in pressure caused due to a high-speed flow of refrigerant when it is jetted from a nozzle part of the ejector, a vapor-phase refrigerant flowing from the second evaporator is drawn. In addition, a speed energy of the refrigerant in expending is converted to a pressure energy by a pressure increasing portion of the ejector to increase the refrigerant pressure, so that a driving force of a compressor can be decreased.
Furthermore, JP-B1-3322263 proposes a refrigerant cycle in which only one evaporator is located between the liquid refrigerant outlet of the vapor-liquid separator and the refrigerant suction port of the ejector. In addition, the refrigerant cycle is provided with an inner heat exchanger which performs a heat exchange between low-pressure vapor refrigerant flowing out of the vapor-liquid separator toward the compressor and high-pressure refrigerant at a refrigerant outlet side of a radiator. In this case, an enthalpy difference between the refrigerant inlet and outlet of the evaporator can be enlarged. However, when the inner heat exchanger is provided for enlarging the enthalpy difference, a superheat degree of refrigerant at the refrigerant suction side of the compressor is increased due to the heat exchange within the inner heat exchanger, thereby reducing the density of refrigerant drawn into the compressor. As a result, the flow rate (mass flow rate) of refrigerant discharged from the compressor may be reduced, and cooling capacity of the evaporator may be also reduced.